Innovative herbicides are rare on the range. Indaziflam is a new range/pasture herbicide owned by Bayer CropScience. It is sold in a concentrated formulation (trade name: Esplanade), as well as a diluted formulation (EsplanadeEZ). This herbicide is important because it selectively controls annual grasses, such as cheatgrass/downy brome, as well as many annual broadleaf plants, such as kocia and Russian thistle. Most native prairie grasses in North America are long-lived perennials, so this has significant implications on rangelands. As a group 14 herbicide, its mode of action is disrupting cell membranes, specifically cellulose biosynthesis. It also has a 180-day residence time, which is especially useful for seasonal control of annual species.
As costs reduce, this herbicide is projected to have widespread application on rangelands, especially in the degraded 'cheatgrass belt' of the Great Basin, as well on the Great Plains. It also presents exciting opportunities as a bare-ground treatment for industrial uses (i.e. DOT, utilities, and railroads). These industries are a major vector for invasive species on rangelands. Its application on rangelands is being pioneered by CSU's College of Agricultural Science at three locations across Colorado (see paper Sebastian et al., 2016). Bayer CropScience is also currently conducting research into establishing a grazing tolerance under a variety of conditions.
Older herbicides still provide low-cost control on range
- Woody shrubs: A basal application of a 25% triclopyr (trade names: Remedy Ultra, PastureGard HL) and 75% diesel oil/kerosene solution provides excellent control of woody species. Apply to the stump or frill immediately after cutting. Best control is achieved in fall, and is improved by dry conditions. Triclopyr is also grazing tolerant.
- Broadleaf plants: Many herbicides are available to control broadleaf plants ("weeds") in rangeland environments. Dicamba (trade names: Banvel, Clarity, Vision) provides excellent control on a variety of broadleaf plants, especially kocia, and is grazing tolerant. Picloram (Tordon 22K, Grazon P+D) is an excellent option for thistles and knapweeds, and is grazing tolerant. Metsulfuron (Cimmaron Plus, X-tra, Max, etc.) is a newer (~ 1990's) broadleaf herbicide and is also grazing tolerant.
- Annual grasses: Imazapic (trade name: Plateau) is grazing tolerant, but has had poor to moderate success on cheatgrass control (less than 50 % kill), and is very expensive. A well-timed glyphosate (Roundup, etc.) application is also often used, but can significantly damage native grasses, requiring a seed bank, or expensive re-seeding.